Authored By Dan Alex (Updated: 11/11/2016):
The Tank Buster in WW2
Tank busting elements played a crucial role in World War 2 where tank-on-tank battles often times moved the war in one direction of the other. As such, all sides delved into the development of aircraft with suitable armament to deal with enemy armor. Perhaps the best known of these became the Junkers Ju 87 Stuka, armed with two underwing cannons pods with the projectile velocity to penetrate the armor of Soviet tanks. This exercise no doubt showcased the value of a dedicated tank busting system but even in the years after the war, no party put forth a capable design, feeling other systems were more than efficient at the CAS role.
The "Warthog" Name
Though officially designated "Thunderbolt II" in April of 1978 in honor of the other exceptional Republic product - the P-47 Thunderbolt of World War 2 fame - the A-10 carried the company tradition of having been given an unofficial name in line with the "hog" reference. The Republic F-84 became the first to use this moniker, being nicknamed "Groundhog" or "Hog" while the F-84F Thunderstreak became the "Superhog" and the Vietnam-era F-105 Thunderchief became the "Ultra Hog". In staying with this tradition, the A-10 Thunderbolt II had unofficially become known as the "Warthog" over the years, due to its less-than-beautiful outward appearance. The name was dropped in a speech given by Major Michael G. Major at the Tactical Air Warfare Center (TAWC) Review. The name stuck with crews but has since evolved to the simpler "Hog" or, perhaps more appropriately, "Hawg". At any rate, the Thunderbolt II official designation and Warthog unofficial nickname are essentially interchangeable when talking about this fine aircraft.
Close-Air Support (CAS)
Close-Air Support (CAS) functions relied on some distinct requirements that would differentiate the design from existing strike fighters. This aircraft could have to operate in the thick of combat actions and become the target of small arms, large caliber ground-based cannons and missile batteries. As such, survival was of the utmost importance for both pilot and machine. The pilot would have to sit in a reasonably armored environment and the aircraft's critical internal operating components (hydraulics, avionics and fuel) would also have to be designed in such a way as to keep the aircraft aloft even after sustaining combat damage that would do in most any other airplane. As a system charged with attacking both heavily armored and lightly (or unarmored) ground targets, the aircraft would have to heavily armed and capable of an impressive payload output. Additionally, as a CAS aircraft, the new design would have to make use of efficient engine power while not expending vital fuel stores, providing the capability of loitering in a target area for hours until called to action by ground forces or command.
The USAF Need
To this point, the USAF had nothing but the so-called "hotrods" in its stable by the time of the Vietnam War. These aircraft, mostly jet-powered, could undoubtedly fly the hairs off of a tick but, in terms of CAS requirements, that also equaled minute-long loitering times and an excessively long turning radius. This type of hyper performance allowed for perhaps one or two passes on a target before having to return home to rearm and refuel. These aircraft were also notorious for long take-off and landing rolls meaning that they required a firm, large area from which to operate from. There was also the issue of inherent complexities in the refueling and rearmament process and limitations to payload capabilities, all pointing to the dire need for a true dedicated CAS aircraft. The propeller-driven Douglas A-1 Skyraiders of the war proved the validity of low-level, close-support aircraft with exceptional firepower, robust qualities and agility at low speeds/low-altitudes but what she lacked was the performance of her mighty jet-powered counterparts.
Republic Becomes Fairchild Republic
Republic Aviation got its start in 1939 after the Seversky Aircraft Corporation ran into financial issues and was reformed un the new Republic name. The new firm, operating out of Farmingdale, New York, was finally able to make something of a marketing and financial splash with their excellent P-47 "Thunderbolt" in June of 1942. The P-47 - known as the "Jug" - was an eight-machine-gun-armed beast that proved suitable in both the fighter role as well as the ground strike role. She went on to be produced more than any other American fighter in World War 2 and made Republic a household name. The Thunderbolt saw extensive use in both Europe and the Pacific and was generally liked by her pilots, though oft-overlooked by most students of the war today, preferring instead to focus on the more sexy P-51 Mustang, Fw 190 or the Supermarine Spitfire. Interestingly, American military use of the P-47 ceased immediately after the war and no plans were made to bring them out of storage by the time of the Korean War. Many supporters of the Jug believed that the hard-hitting qualities of the P-47 in that conflict would have made a difference.
Nevertheless, the post-war world was the jet's age of enlightenment. Naturally, Republic jumped into the fray and developed the single-engine F-84 fighter series that encompassed the straight-winged F-84D "Thunderjet", its swept-wing cousin the F-84F "Thunderstreak" and the dedicated reconnaissance platform the RF-84F "Thunderflash". Thunderjets proved valuable in the Korean War and many served up until the early 1970s with Air National Guard units before reaching their inherent usefulness.
Next on the Republic drawing boards proved to be the large and complex, but ultimately dominant, F-105 Thunderchief. This single-engined monster became the largest USAF-serving fighter to date and saw extensive service in the Vietnam War, undertaking a variety of roles including strike and reconnaissance sorties. She served primarily in the ground attack role until replaced by the excellent multi-role, twin-engine, two-seat McDonnell Douglas F-4 Phantom II. Of the 833 Thunderchief systems delivered, 397 of these would be lost to action in the skies over Vietnam.
Republic attempted several forays into the civilian and passenger airliner markets but failed on to generate much interest let alone revenue. The company fell on hard times and a last-ditch effort to sell the USAF on an attack aircraft had failed. Republic Aviation was acquired in full by Fairchild in July of 1965.
Fairchild began as the Fairchild Aviation Corporation in 1929 and became Fairchild Hiller in 1964 after the purchase of Hiller Aircraft. They then became Fairchild Industries in 1971 following the death of founder Sherman Fairchild. The A-10 Thunderbolt II would be marketed under the joint Fairchild Republic name. Beyond the A-10, Fairchild continued to evolve and was renamed Fairchild Dornier after taking over the civilian side of the German aircraft company in 1996. Today, Fairchild has been absorbed by the German insurer Allianz A.G., along with the American company, Clayton, Dubilier & Rice, Incorporated, and operates under the M7 Aerospace branding.
The AX Competition
The AX ("Attack Experimental") program began in June of 1966 with a detailed requirement put together in September of that year. On March 6th, 1967, the USAF put forth a Request for Information (RFI) to no fewer than twenty-one trusted defense contractors. Follow-on study contracts were then awarded to General Dynamics, Grumman, Northrop and McDonnell on May 2nd of 1967 in an effort to find the best arrangement of protective armor, internal systems and fuel on a new design centering on survivability and firepower. The program's high-reaching goal was to develop a highly-sustainable dedicated CAS aircraft to fulfill the need so painfully unveiled in the Vietnam War. Should full-scale war develop in Europe through a Soviet land invasion involving tanks, infantry and support vehicles, NATO would need to respond to such force with equal force itself - dealing with targets in the thick of night or in the adverse weather conditions so common throughout the European mainland. The new aircraft would replace the outmoded Douglas A-1 Skyraider in the role for the USAF. It was thought best that the new aircraft should make use of two turbofan engines to remove the need (and required area) for the operation of spinning propeller blades as well as allow for operations on a single engine if need be. Responses were delivered from Boeing, Cessna, Fairchild Republic, General Dynamics, Lockheed and Northrop on August 10th, 1970.
An additional requirement in the AX competition called for the aircraft to be armed with a massive rotary 30mm cannon, one of the largest production armaments to ever be fitted in a combat aircraft. The 20mm M61 Vulcan cannons of the Vietnam War-era aircraft proved sufficiently enough against other air targets but it was woefully insufficient to combat armored targets of value. Combat experience, even those recorded as far back as World War 2, shown a need for a large caliber repeating weapon to affect enemy armor at range and from the air.
Two companies were selected as the early winners, this being Northrop and Fairchild Republic. Each company was granted design, development and construction of two prototype aircraft to be designated as the YA-9A and the YA-10A respectively. For Republic, it was a shot in the arm, their assembly lines now running cold since production had ended on the F-105 Thunderchief.
The Northrop YA-9
The Northrop submission was quite conventional at its core, appearing in some ways like the Sukhoi Su-25 "Frogfoot" combat platform with its straight-winged, multi-hardpoint design running along a slender semi-monocoque fuselage with a riveted stressed aluminum skin. The cockpit was held well-forward in the design, offering up good forward and side views out over the short nose assembly. Wings were shoulder-mounted and fitted amidships, with clipped wingtips. Wing surface area was large to promote additional drag as well as offer up ten strong underwing hardpoints for varying ordnance loads. Engines were fitted to the lower portion of the central fuselage and held some distance apart from one another for survivability . The empennage was traditional and tapered off into a large-area, single vertical tail fin sporting two upward-angled stabilizers. When at rest, she sat low to the ground on a conventional tricycle undercarriage, all with single wheels. The undercarriage was made up of two main landing gear legs retracting into each engine assembly side and a nose landing gear leg retracting under the cockpit floor. The nose leg was offset to the portside to make room for the intended 30mm nose cannon, though an 20mm M61 Vulcan was fitted in the interim. Fuel tanks were fitted inside of each wing assembly outboard of the engine placement. Flight controls were made redundant to promote survivability from direct hits. The pilot sat in an armored "tub" made of aluminum, though production aircraft would feature titanium. Engines were a pair of developmental Lycoming YF102 series turbofans.
What made the YA-9 most unique was the inclusion of the Side-Force Control (SFC) system that integrated movements of the speedbrakes with the rudder to prevent "slideslip". This helped the pilot to maintain the proper angles on a target without banking the aircraft to the extreme, only to have to realign his aim once again. This feature was made optional to the pilot, to be used as he saw necessary, but was thought to grant the YA-9 a heightened form of accuracy in munitions delivery.
In practice, the YA-9 prototypes flew well, totaling some 146 hours through 92 flights. Her first flight was on May 30th, 1972, twenty days after the YA-10, with Lew Nelson at the controls. Handling characteristics were found to be better than that of the competition, with less roll inertia, and the SFC system itself proved a success.
The YA-10, on the other hand, was a different sort of creation. Its unorthodox design immediately made it stand out from the competition. She handled well when going airborne for the first time on May 10th, 1972 out of Edwards Air Force Base (AFB) with Howard "Sam" Nelson (unrelated to Northrop's Lew Nelson) at the controls. The second flight ended with some flat tires but nothing serious. The YA-10 fitted its engines high on the fuselage, away from ground fire and debris typical of unprepared runways. The wings were large and straight formed, encouraging drag and low-speed, low-level flight with split airbrakes fitted to each wing trailing edge. Like the YA-9, the YA-10 gave its pilot an excellent view from his seat. Internally, the YA-10 also featured redundancy in controls and subsystems. The second YA-10 went airborne on July 21st, 1972.
The USAF looked at each aircraft closely, with evaluation of the systems proceeding concurrently from October 10th, 1972 to December 9th, 1972. While both airframes exceeded the USAF expectation, the Republic YA-10 evaluation slightly outmatched the Northrop submission on a variety of fronts. The YA-10 was a more structurally "ready" pre-production aircraft than the prototype form offered by Northrop, potentially allowing for quicker full-scale production once development commenced. Pilots generally believed in the unique layout of the YA-10 and its inherent survivability qualities when compared to the conventional Northrop submission. The low-set wings of the YA-10 was also noted for its promotion of quick rearming. This was in contract to the high-mounted wings on the YA-9. The Republic design was also slated to make use of the existing TF34 turbofan engine series already in use by the USAF and the USN. As such, there would be little in the way of engine development to slow the program down.
Like most any multi-million dollar deal regarding the American military, these competitions are almost always decided on the political front. The Republic firm was going through some tough times and they represented the relatively small aeronautical presence in the state of New York along with Grumman. Southern California, where Northrop was based, had long held a strong position in the aviation industry. It would seem that Republic and the state of New York could use the AX contract to keep constituents happy.
With all the results in, and all factors accounted for, the USAF announced Fairchild Republic as the winner of the AX program on January 18th, 1973. The contract amounted to $159,279,888 and called for ten YA-10A developmental models plus two additional airframes. An option was included for 48 first-run production aircraft after the development of the GAU-8/A 30mm cannon was completed. General Electric received $27,666,900 for the development of a slightly modified TF34 engine that could be made interchangeable on the new YA-10 regardless of whatever fuselage side it was mounted to. The production contract was signed on March 1st, 1973.
On the losing front, the Northrop YA-9 prototypes were sent to NASA in the hopes they could be of some use to the space industry. The space agency never found a home for the YA-9s and sent them to the museums at Edwards AFB and March Field to be kept as showpieces.
Not a Done Deal
Despite the announcement, the USAF still needed to prove the expensive requirement for a dedicated CAS aircraft to its detractors. Every major program, considering the amount of money involved, always faced an uphill battle even along the political front. The YA-10 proved no exception and felt the heat from a congressional Texas delegation bent on drumming up more business for their closing Vought A-7 Corsair production lines. The members argued that a modified A-7D model, this projected with a long fuselage housing the new GE 30mm cannon, could more effectively fulfill the CAS role than the all-new - and inherently expensive - YA-10. The US congress recommended a fly-off between the Corsair and the Thunderbolt but the USAF was slow to respond. When the congress cut funding to four preproduction YA-10As, the USAF finally jumped to action and commenced with the competition. The fly-off occurred from April 16th to May 10th, 1974 and the results were encouraging to the Republic product, showing their ugly aircraft to be the superior breed in the CAS aircraft class. The YA-10 was able to loiter in a designated target area for up to two hours against the A-7Ds menial 11 minutes of flight time. Consideration for the A-7 as a CAS aircraft was dropped and the YA-10 lived to fight another day.
The first prototype YA-10 was put in "flyable" storage on April 15th, 1975 - her work now complete. Her resume included 467 flights totaling nearly 510 hours of flight time. The second prototype soon followed suit and was placed in storage on June 13th, 1975 after amassing 354 flights totaling nearly 549 hours of flight time. Six preproduction aircraft would soon take their places beginning in February of 1975 with each one charged a different program goal. The sixth preproduction example was later lost to a double engine flame out on June 8th, 1978, the pilot ejecting safely with his Douglas ESCAPAC ejection seat. Despite testing moving along rather comfortably, the lack of further preproduction examples inevitably led to program delays. A further delay occurred after test pilot Sam Nelson was tragically killed while conducting a series of low-level loops at the 1977 Paris Air Salon at Le Bourget. Otherwise, Thunderbolt testing revealed little in the way of major flaws in the unorthodox design.
The 6510th Test Wing of the Air Force Flight Test Center out of Edwards AFB and the 3246th Test Wing at Elgin AFB were two of the earliest recipients of the prototype and preproduction YA-10 examples. These groups became the first such USAF entities to handle the aircraft. The 3246th was of particular note for they handled the required armament trials.
Republic production facilities were not on par with the latest offerings found in her defense competitors. Luckily, the A-10 was not a highly-advanced aircraft requiring the latest in technologies to put her together. However, the USAF expressed concerns about the delays in production and ordered Republic facilities to be brought up to speed at the company's expense. This was done to the USAF's pleasure but hurt Republic's bottom line in the process. Production aircraft were very similar to the preproduction forms with a few slight exceptions. Ventral strakes were added and leading edge slats were now fixed. The wingspan was increased out some 30-inches while the flap angle was adjusted. A laser receiver for the the AN/AAS-35(V) PAVE PENNY was added to the right side of the forward fuselage to be used in conjunction with laser-guided munitions (PAVE PENNY searches for the reflected laser light applied to a target by other ground-based "friendlies"). While preproduction aircraft were fitted with the Douglas ESCAPAC ejection seat system, production models utilized the McDonnell ACES II series.
Final assembly of production A-10s was moved to Hagerstown, Maryland. The first production A-10A achieved flight on October 10th, 1975. Delivery was delayed some five months before the 355th TFW received their first A-10As in March of 1976, ironically replacing their outgoing Vought A-7 Corsair IIs. The 355th carried out the required test and evaluation of the A-10A and took part in the 1977 Joint Air Weapons System (JAWS) trials. These trials would prove crucial in developing the tactics and defining the true battlefield role of the new A-10A once in operational service and its relation to the existing battlefield components such as artillery and attack helicopters - the latter essentially sharing the same tank-killing role as the A-10. The first operational A-10 squadron appeared in October of 1977 as the 333rd Tactical Fighter Training Squadron (the "Lancers") and they were soon joined by the 358th TFTS "Lobos". The 354th Tactical Fighter Wing out of Myrtle Beach produced the 353rd, 355th and the 356th Tactical Fighter Squadrons. The designation of "Thunderbolt II" was officially assigned by the Pentagon on April 3rd, 1978, in a ceremony commemorating the 100th production A-10 airframe. The final A-10 was delivered to the USAF in 1984.
The 81st Tactical Fighter Wing based out of England took delivery of their A-10As after the trials and evaluations were completed. Since the battlefield was undoubtedly to be European in nature, this fighter wing became one of the important early operators of the new aircraft. The first A-10A arrived on January 26th, 1979, and ultimately was fielded by no less than six squadrons - the 78th, 91st, 92nd, 509th, 510th and the 511th Tactical Fighter Wings. From their bases in England, the A-10A could be deployed to six awaiting Forward Operating Locations (FOLs) across West Germany. The 81st was eventually branched off in 1988 to form the 10th TFW based out of RAF Alconbury.
Five Air National Guard (ANG) state-side squadrons were set up to help reinforce the 81st stationed in Europe in the event of total war. These became the 103rd TFS out of Connecticut, the 104th TFS out of Massachusetts, the 128th TFS out of Wisconsin, the 174th TFS out of New York state and the 175th TFS out of Maryland. The 103rd was the first to receive their A-10As beginning in May of 1979.
The Air Force Reserves were the next recipients for the A-10A. The 917th TFW took delivery of their examples in October of 1980. They were joined by the 442nd TFW, the 926th TFW and the 930th TFW. Other groups soon followed and included the 23rd TFW out of England AFB in Louisiana as well as the 51st Composite based in South Korea and the and 343rd Composite based in Alaska. The latter two groups took delivery of their systems from 1981 into 1982.
Externally, the A-10's appearance became its defining characteristic. No other aircraft had ever taken on its seemingly unorthodox layout and no other aircraft has since copied its success. Since the role dictated the design, the A-10 made use of several key layout features that defined her legacy. Her fuselage was of a slender shape with a short nose assembly, slab sides and tapering downwards to the empennage. The underside of the fuselage was well-flat from nose to tail. Electrical equipment was fitted to the rear of the cockpit while the 30mm cannon and applicable ammunition drum took up most of the forward fuselage with the cockpit and forward landing gear. The left main and right main fuel tanks were situated in tandem just aft of the electrical equipment area with the right main tank coming first in the layout and the left following. Many of the internal systems of the A-10 were made readily accessible by way of large hinged access panels. These panels dotted the fuselage to help make maintenance and repair a somewhat easier process when compared to other aircraft.
The A-10 Cockpit
The cockpit was held well-forward in the design and sported a two-piece raise canopy to allow the pilot excellent views forward and to the sides of his/her aircraft. It was set ahead of the wings and even offered views to the ordnance loads to be held under each wing assembly while offering a limited glance to each engine mounted further aft - useful in battle damage assessment. The pilot sat in a raised position in a relatively spacious cockpit. His ejection system was the high-backed ACES II series ejection seat. The rear portion of the canopy was hinged at the base and powered. The forward canopy was divided by framing and sat over a HUD (Heads-Up Display) system atop the instrument panel. The forward canopy could resist blows from a 20mm cannon. To each side of the HUD were the accelerometer (on the left vertical frame post) and a standby compass (on the right vertical frame post). The rest of the canopy glass was bulletproof to an extent. The instrument panel itself was well-organized and in many ways reflected Republic's experience in the development and production of their jets sometime before. The throttle was set low and to the left of the pilot's leg while the control stick was situated conventionally between the pilot's legs. Interestingly, the Warthogs initially featured no autopilot function, requiring the operator to maintain complete situational awareness on the longest of flights. This was thankfully rectified by way of a modernization program some time later.
One of the most noteworthy design elements of the cockpit was its situation within a titanium armored "tub". Despite its name, the "tub" was actually nothing more than titanium slabs bolted together as opposed to a single forged unit. The tub offered protection from 23mm projectiles from below, the front, sides and rear. Only the rear titanium panel held openings for hydraulic, electrical and other control systems.
The A-10 Instrument Panel
The instrument panel appeared quite conventional by modern standards. The center was dominated by the traditional attitude director indicator and horizontal situation indicators. Just above those and offset slightly to the left was the radar warning system that alerted the pilot to radar tracking, targeting and engagement by enemy systems. The azimuth direction scope indicator was to the left of the warning system. All weapons controls were congregated into an easy-to-reach panel subset spaced to the lower left, just above and ahead of the pilot's left kneecap. Each underwing pylon could be controlled from this collection of switches and the pilot could further keep track of the 30mm rounds available to the nose cannon via a simple counter. Later A-10s fitted a slightly revised armament panel to incorporate use of the self-defense AIM-9 Sidewinder air-to-air missile capability. Armament controls were extended to the throttle and control stick as well. Undercarriage functions were accessed along the lower left. Additional flight controls were seated along the upper left of the forward instrument panel. The lower right of the panel contained all engine controls and applicable function gauges including the fuel indicator. Above this collection was the Maverick missile television screen. This served to target and guide the Maverick air-to-surface missiles through pinpoint accuracy. Of note in the cockpit were the three yellow-and-black "FIRE PULL" handles running across the top of the instrument panel. Each controlled different onboard fire extinguishers and could be pulled by the pilot in the event of a fire. The left and right handles controlled the extinguishers for each respective engine. The center handle offered extinguishing aid to the Auxiliary Power Unit (APU) when needed. The instrument panel could be further accessed (by technicians) in that it hinged forward to allow for easier access. The center console ran ahead and between the pilot's legs, this area holding the Laser Spot Seeker Panel and the Essential Circuit Breaker Panel. The left console was afforded an area to collect the "piddle packs" of urine, made available for the A-10 pilot to relieve himself with on long flights.